A static pressure generated by two and more fans serially connected could be doubled when a wind capacity is zero. Each additional fan connected serially can increase wind capacity in a higher static pressure system. As a result, serially-connected fans can be a solution addressing an optimized effect to a system with high resistance.
As vibration always comes with rotation of fan, the only difference regarding vibration is the intensity thereof. In general, the higher static pressure and the bigger blades a fan has, the more critical vibration it will cause. Besides, vibration not only results in noise but also lessens system reliability, leading to premature fatigue and aging of electronic devices inside a system and shortening the life span of the system.
As shown in FIG. 1, the serially arranged fans at least includes two fan frames 10, which provide corresponding retaining parts 11 and grooves 12 respectively so as to get the two fan frames 10 serially engaged.
The fan frame 10 has a hollow containing space therein for accommodation of a fan rotor (not shown), and a base 13 is disposed at one end of the containing space and is integrally integrated with the fan frame 10 by means of a plurality of ribs 14. The base 13 is provided for mounting a driving device (not shown and not depicted in the present invention further as the operation of the fan rotor and the driving device is a conventional technique and is not associated with the present invention directly) that is used to drive the fan rotor to rotate. The holes between the ribs 14 are provided as a passage for air flow circulation.
As the two fan frames 10 are directly contacted and serially integrated in the aforementioned serially-connected fan, the resulting shortcomings are concluded as follows:
Severe resonant condition due to serial connection of the two fan frames 10: The design concept of motor rotation by torque will inevitably generate vibration. Especially when the fan rotors inside the two fan frames 10 of the serially-connected fans rotate simultaneously, the two fan frames 10 will generate severe resonant effect resulting from the interaction of the fundamental frequency of vibration generated by the two fan frames 10, and the resonant effect will be transmitted to system, making system fail to perform its optimized efficacy.
Shorter life span arising from the resonant effect: When a system is subjected to resonant effect over a long period of time, such effect not only accelerates the premature fatigue and aging of the contact points of electronic devices but also shortens the life span of the system.
Acute noise out of vibration: Resonant effect also gives rise to gigantic noise, which impacts on the entire noise value assessment of system remarkably.
Consequently, to completely solve the resonant issue of the aforementioned serially-connected fan frames and maintain the optimized performance and the life cycle of the system, a more positive damping and shock-absorbent measure to lower fundamental frequencies of vibration of the serially-connected fan frames and get rid off interaction and transmission of vibration amplitude resulting from rotation of the fan rotor shall be in place. In that sense, developing a shock-absorbent structure for serially-connected fans is indispensable.